At 14 words – "Only marriage between a man and a woman is valid or recognized in California" – Proposition 8 may be the shortest initiative on record, but it has spawned a deep stack of legal arguments over amending the California Constitution.

Its opponents contend this is no mere constitutional amendment. They say it's a constitutional "revision" – in other words, a change to the state's legal foundation so profound that it can't be accomplished through the initiative process. A revision requires passage by two-thirds of the Legislature or by a constitutional convention and, only then, by a majority of the state's voters.

The California Supreme Court last week agreed to hear that argument and another possible legal theory that might be used to strike down Proposition 8: that it violates the separation of powers doctrine by interfering with the duty of the courts to ensure equal protection of the laws. A decision seems likely by next summer. In the meantime, the court has refused to block enforcement of Proposition 8, meaning no additional same-sex marriage licenses can be issued.

Normally the Supreme Court's acceptance of a case is seen as a preliminary victory for the petitioners. That's particularly true when the court already has sided with them in a prior case, as this court did when it ruled in the strongest possible legal terms in May that gay and lesbian couples have the same right to marry as opposite-sex couples. It became the first court anywhere to rule that judges must treat all laws discriminating against gays and lesbians with great skepticism, just as they approach laws that put racial minorities at a disadvantage.

But Wednesday's announcement that the court would wade back into the same-sex marriage controversy was applauded on all sides. The sponsors of Proposition 8 and Attorney General Jerry Brown had joined the opponents in urging the justices to clear up the outstanding legal issues as quickly as possible.

This is a new case with new issues, and there's no way of guessing what the outcome will be. Only Justice Carlos Moreno seems to be signaling that he views Proposition 8 as unconstitutional. He voted to stay enforcement of the initiative while the case is being decided.

Another justice, Joyce Kennard, who was a member of the 4-to-3 majority ruling in favor of same-sex marriage last spring, may now be leaning in favor of upholding Proposition 8. She dissented from the justices' vote to take up the new case, explaining only that she might be willing to consider a case confined to the question of whether the marriages performed before Nov. 4 remain valid.

The court said it will rule on those 18,000 same-sex marriages if it upholds Proposition 8. This issue, too, could go either way. The justices invalidated about 4,000 marriages after San Francisco Mayor Gavin Newsom ordered the city clerk to grant marriage licenses to same-sex couples in 2004 because the marriages had not been properly authorized. That's not the case with the new marriages, and Brown, for one, says the initiative would not be retroactive. On the other hand, the initiative language – "is valid or recognized" – seems to imply retroactivity, and Proposition 8 sponsors can be expected to argue the point forcefully.

The preliminary arguments filed with the court in the past couple of weeks – by same-sex couples, civil rights groups, cities and counties and 44 California legislators – rely on the theory that Proposition 8 is a constitutional revision, which can't be enacted by initiative.

The concern is the effect Proposition 8 would have on the "equal protection of the laws" provision in the California Constitution. A fundamental constitutional principle, equal protection has been interpreted more expansively under the California Constitution than under the U.S.Constitution. As a result, California has long been the nation's leader in forging protections for unpopular minorities. For example, the California court upheld interracial marriages in 1948, two decades before the U.S. Supreme Court did. Because equal protection means equal treatment for all, creating an exception for gays and lesbians by a simple majority vote of the people would render the concept meaningless, opponents of Proposition 8 have argued in the preliminary briefs filed after the Nov. 4 vote.

Claire Cooper, former legal affairs reporter for The Bee, is a Bay Area freelance writer.